U.S. patent application number 10/945425 was filed with the patent office on 2005-07-07 for composite dual lcd panel display suitable for three dimensional imaging.
This patent application is currently assigned to NeurOK LLC. Invention is credited to Lukyanitsa, Andrew.
Application Number | 20050146787 10/945425 |
Document ID | / |
Family ID | 36090569 |
Filed Date | 2005-07-07 |
United States Patent
Application |
20050146787 |
Kind Code |
A1 |
Lukyanitsa, Andrew |
July 7, 2005 |
Composite dual LCD panel display suitable for three dimensional
imaging
Abstract
A three-dimensional imaging system and related methods is
provided that utilizes a composite transmissive LCD panel. The
composite LCD panel contains at least two layers of stacked liquid
crystal cells positioned on top of one another relative to the
imaging direction, is utilized to display at least two calculated
images superimposed over one another at different distances within
the panel from the viewer. Each layer of liquid crystal cells
create multiple pixels from the cells, which pixels collectively
can be operated to form independent images on each liquid crystal
layer. The composite LCD panel can be used to create a continuous
3-D image field in a large viewing area or in multiple viewing
areas in conjunction with a suitable 3-D image generation
system.
Inventors: |
Lukyanitsa, Andrew; (Moscow,
RU) |
Correspondence
Address: |
HOGAN & HARTSON LLP
IP GROUP, COLUMBIA SQUARE
555 THIRTEENTH STREET, N.W.
WASHINGTON
DC
20004
US
|
Assignee: |
NeurOK LLC
|
Family ID: |
36090569 |
Appl. No.: |
10/945425 |
Filed: |
September 21, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10945425 |
Sep 21, 2004 |
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10751654 |
Jan 6, 2004 |
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10751654 |
Jan 6, 2004 |
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09977462 |
Oct 15, 2001 |
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6717728 |
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09977462 |
Oct 15, 2001 |
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09456826 |
Dec 8, 1999 |
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Current U.S.
Class: |
359/462 ;
348/E13.029; 348/E13.03; 348/E13.038; 348/E13.04; 348/E13.045;
348/E13.046; 348/E13.049; 348/E13.05; 348/E13.057; 348/E13.059;
348/E13.066 |
Current CPC
Class: |
H04N 13/31 20180501;
H04N 13/337 20180501; G02B 30/52 20200101; H04N 13/341 20180501;
H04N 13/368 20180501; H04N 13/189 20180501; H04N 13/305 20180501;
H04N 13/366 20180501; H04N 13/361 20180501; G02F 1/13471 20130101;
G03B 35/24 20130101; H04N 13/395 20180501; G02B 30/34 20200101;
H04N 13/376 20180501; H04N 13/349 20180501; G02B 30/25 20200101;
G02B 30/27 20200101; H04N 13/302 20180501; H04N 13/373 20180501;
H04N 13/117 20180501; H04N 13/359 20180501; H04N 13/351 20180501;
H04N 13/398 20180501 |
Class at
Publication: |
359/462 |
International
Class: |
G02B 027/22 |
Claims
What is claimed is:
1. A method of creating a three-dimensional image display,
comprising: determining at least one viewing zone located in front
of a composite liquid crystal display panel, said composite liquid
crystal display panel containing at least two independent liquid
crystal cell layers capable of imaging two different images, said
cell layers spaced one in front of another relative to said viewing
zone; displaying different images on each said cell layer; and
backlighting said cell layers to display a stereoscopic image
visible in said at least one viewing zone wherein said visible
image corresponds to a selected pair of source stereopair
images.
2. The method of claim 1, wherein said displayed images are
calculated images processed from said source stereopair images, and
wherein processing for each said calculated image comprises
iteratively: estimating the light directed to each one of a
viewer's eyes by calculating interim calculated images for each of
said cell layer, and then determining the light directed through
each of a plurality of discrete pixels of a front one of said cell
layers; comparing the estimated light for each pixel with the
equivalent light from the selected one of said stereopair images to
determine an error; adjusting said interim calculated images to
reduce said error; and accepting said interim calculated images as
said calculated images once said error for each pixel is below a
set limit.
3. The method of claim 2, wherein said processing of said selected
source stereopair images is performed by an artificial neural
network.
4. The method of claim 1, wherein said at least one viewing zone is
determined by a calculation responsive to a sensed viewer position
signal.
5. The method of claim 1, wherein said at least one viewing zone is
continuously monitored by an automated viewer position sensor that
generates a signal used in producing said calculated images.
6. The method of claim 1, wherein said calculated images are
processed according to a plurality of viewing zones.
7. The method of claim 1, further comprising selecting a plurality
of said stored stereopair images for display to a plurality of
viewing zones, and wherein said two calculated images are produced
by processing said selected stereopair images.
8. The method of claim 1, wherein an input orientation surface of a
first one of said liquid crystal cell layers in said composite
liquid crystal panel is arranged orthogonally with respect to
polarization to an input orientation surface of a second one of
said cell layers.
9. The method of claim 8, wherein said cell layers are separated by
transparent glass.
10. The method of claim 1, wherein said liquid crystal cell layers
are of the active matrix type.
11. The method of claim 1, wherein said selecting of said source
stereopair images is performed according to said determined viewing
zone, and wherein movements of said selected viewing zone impacts
said selecting of said one of said stereopair images.
12. The method of claim 1, wherein said viewing zone is determined
automatically to correspond to a variable position of an intended
viewer of said visible image, and wherein said selected source
stereopair images are changed as the position of said viewer
varies.
13. The method of claim 12, wherein said changing of said source
stereopair images comprises selecting a different source stereopair
that corresponds to a different perspective of said selected source
stereopair.
14. The method of claim 11, wherein said changing of said source
stereopair images comprises selecting a different source stereopair
that corresponds to a different perspective of said selected source
stereopair.
15. The method of claim 1, further comprising determining at least
two viewing zones and selecting at least two pairs of source
stereopair images, a first pair of said selected source stereopair
images corresponding to a first determined viewing zone and a
second pair of said selected source stereopair images corresponding
to a second determined viewing zone such that said calculated
stereopair images causes said displays to create two different
visible stereoscopic images, a different one of said two different
stereoscopic images being visible in each said at least two viewing
zones wherein said visible images corresponds to said selected
pairs of source stereopair images.
16. A dynamic three-dimensional image display, comprising: a source
of stereopair images; a composite liquid crystal display panel
containing at least two transmissive liquid crystal cell layers,
said layers spaced one in front of another relative to a display
viewing area and adapted to independently produce different images
from one another; an illumination source to backlight said cell
layers to said display viewing area; a processor; and a video
controller electronically interfaced with said displays, said
illumination source and said processor; wherein said processor
operates logic adapted to determine at least one viewing zone
within said viewing area, to select a pair of source stereopair
images, and to produce two calculated images derived from said
source stereopair images and said relationship of said viewing zone
and said layers, said calculated images being derived so that they
act as a mask for each other when imaged on said layers, a first
one of said calculated images being adapted for a front one of said
layers and a second one of said two calculated images being adapted
for a rear one of said layers; and wherein said video controller
receives calculated image data from said processor and causes each
display to generate an appropriate one of said calculated images
such that each displayed calculated image acts as a mask for the
other displayed calculated image to display an three-dimensional
image visible in said at least one viewing zone, said visible image
corresponding to said selected pair of source stereopair
images.
17. The display of claim 16, wherein said processor logic for
deriving each said calculated image comprises the iterative process
of: estimating the light directed to each one of a viewer's eyes by
calculating interim calculated images for each of said layers, and
then determine the light directed through each discrete pixel of
said front layer; comparing the estimated light for each pixel with
the equivalent light from the selected ones of said stereopair
images to determine an error; adjusting said interim calculated
images to reduce said error; and accepting said interim calculated
images as said calculated images once said error for each pixel is
below a set limit.
18. The display of claim 17, wherein said means for processor logic
for deriving each said calculated image is performed by said
processor by emulating an artificial neural network.
19. The display of claim 16, further comprising a viewer position
sensor that provides a signal for said processor to determine said
least one viewing zone based upon the sensed position of a
viewer.
20. The display of claim 19, wherein selecting of said source
stereopair images is dependent upon a location of said determined
viewing zone, and wherein movements of said selected viewing zone
impacts said selecting of said one of said stereopair images.
21. The display of claim 16, wherein said viewing zone is a
stationary viewing zone preset in a memory accessible by said
processor.
22. The display of claim 16, wherein said processor logic derives
said calculated images such that they can be displayed to a
plurality of viewing zones to create an three-dimensional image
visible in each of said plurality of viewing zones.
23. The display of claim 16, wherein said processor logic for
selecting is adapted to select a plurality of said stereopair
images, and where said means for processing is further adapted to
process said plurality of selected stereopair images to calculate
said calculated images such that they can be displayed to a
plurality of viewing zones to create a plurality of aspects of a
three dimensional image visible in said viewing zones.
24. The display of claim 16, wherein said liquid crystal cell
layers each contain an input orientation surface corresponding to a
polarization direction, and wherein said composite liquid crystal
panel is constructed whereby the input orientation surface of a
first one of said cell layers is arranged orthogonally with respect
to polarization to the input orientation surface of a second one of
said cell layers.
25. The display of claim 24, wherein said cell layers are separated
by a hard and optically transparent material.
26. The display of claim 16, wherein said liquid crystal cell
layers are of a type suitable for active matrix liquid crystal
displays.
27. The display of claim 16, wherein said viewing zone is
determined automatically to correspond to a variable position of an
intended viewer of said visible image, and wherein said selected
source stereopair images are changed by said processor as the
position of said viewer varies.
28. The display of claim 27, wherein said processor changes said
source stereopair images by selecting a different source stereopair
that corresponds to a different perspective of said selected source
stereopair.
29. The display of claim 27, wherein said changing of said source
stereopair images comprises selecting a different source stereopair
that corresponds to a different perspective of said selected source
stereopair.
30. The display of claim 16, wherein said processor logic is
further adapted to determine at least two viewing zones within said
viewing area and to select at least two pairs of source stereopair
images, a first pair of said selected source stereopair images
corresponding to a first determined viewing zone and a second pair
of said selected source stereopair images corresponding to a second
determined viewing zone such that said calculated stereopair images
causes said displays to create two different visible stereoscopic
images, a different one of said two different stereoscopic images
being visible in each said at least two viewing zones wherein said
visible images corresponds to said selected pairs of source
stereopair images.
31. The display of claim 16, further comprising a memory in
communication with said processor; said memory containing a
database of various pairs of source stereoscopic images.
32. The display of claim 16, further comprising a mechanism for
receiving source stereoscopic images input selected from the group
consisting of one or more pairs paired video streams, one or more
paired images of objects, and one or more paired views of 3-D
scenes.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] The present Application is a Continuation-in-Part of U.S.
patent application Ser. No. 10/751,654, filed Jan. 6, 2004, which
in turn is a Continuation-In-Part of U.S. patent application Ser.
No. 09/977,462, filed Oct. 15, 2001, now U.S. Pat. No. 6,717,728,
which in turn is a Continuation-In-Part of U.S. patent application
Ser. No. 09/456,826, filed Dec. 8, 1999, all three of which are
incorporated herein by reference in their entirety.
FIELD OF THE INVENTION
[0002] This invention relates generally to composite liquid crystal
display panel constructions for use in three dimensional displays
and other related apparatus. More specifically, the present
invention pertains to three-dimensional visualization and
multi-viewer and multi-aspect imaging employing such composite
liquid crystal display panel constructions and parallel information
processing of known images.
BACKGROUND OF THE INVENTION
[0003] Objects are seen in three dimensions because light reflects
from them and generates a light field in space. The two eyes of a
viewer perceive this light field differently due to their different
locations in space relative to the object, and the brain of the
viewer processes the different perceptions of the light field by
the two eyes to generate three-dimensional ("3-D") perception. If a
second light field (LF') is artificially recreated that is the same
as a first, original light field (LF), the viewer of LF' will see
the same object image in three dimensions. The basic quality of any
3-D imaging system therefore depends on the magnitude of the
difference between LF and LF', or, in other words, how close the
imaging system can come to artificially recreating LF.
[0004] U.S. Pat. No. 5,745,197, issued to Leung et al, discloses a
"volumetric" display intended to provide a type of 3-D imaging
capability. As disclosed therein, the Leung et al. volumetric
display creates viewable 3-D images that have real physical height,
depth, and width by activating actual light sources at various
depths within the volume of the display itself. In this manner, the
two eyes of the viewer perceive various image elements at different
depths within the volume of the display in perspective, thus
creating a 3-D effect. The Leung et al. volumetric display utilizes
a physical deconstruction of a 3-D object that entails "slicing"
the object into pieces by planes oriented perpendicular to the view
path of the viewer. Images corresponding to the resulting slices
are then displayed superimposed on a stack of transmissive display
screens (corresponding to the perpendicular slicing planes) layered
at sequentially increasing distances from the viewer. The
volumetric display thereby creates the appearance of a three
dimensional image by reproducing individual cross sections of a
contoured object on a series of screens wherein images on the
screens closer to the viewer are stacked on top of more distant
image pieces. Therefore, a three-dimensional effect is created in
essentially a mechanical fashion. This type of volumetric display
requires the layering of two or more transmissive imaging display
panels to create the effect of depth, so its three-dimensional
effect is limited necessarily by the depth, number and distance
between the various display screens on which the image slices
appear. Suitable display panels for this purpose include
transmissive liquid crystal display screens.
[0005] Stereoscopic imaging is another technique utilized to
simulate three-dimensional images to viewers. Stereoscopic displays
operate by providing different yet corresponding perspective images
of the same object or scene to the left and right eyes of the
viewer. The viewer's mind thereby processes these two images to
produce a perception of three dimensions. The principles of
stereoscopic imaging have been applied to various areas for many
years, including to the training of professionals, such as pilots
to physicians, and to entertainment, such as 3-D movies and
computer games. All stereoscopic systems rely upon one or more
certain techniques to segregate images for the right and left eyes.
Typically, stereoscopic imaging systems utilize special parallax
barrier screens, headgear, or eye wear to insure that the left eye
sees only the left eye perspective and the right eye sees only the
right eye perspective.
[0006] U.S. Pat. No. 6,717,728, issued to Putilin et al. and
commonly owned by the assignee of the present invention, discloses
an autostereoscopic 3-D display that provides real-time and high
resolution 3-D imaging capability without utilizing parallax
barriers or specialized headgear. The Putilin et al. display
utilizes an image processing algorithm to generate two or more
calculated images from base stereopair images, which are the images
that one ultimately wants to deliver to the two eyes of the viewer.
A first one of those calculated images are sent to a distant
display and the other one or more calculated images are sent to one
or more transmissive displays placed in front (relative to the
viewer position) of the distant display. Each display therefore
simultaneously displays the calculated images that each contain at
least some of the image information destined for each eye of a
viewer. Each display's calculated image, when viewed simultaneously
by a viewer, acts as a mask for and combines with the other
displayed calculated images, resulting in the two different
stereoscopic images being provided to the left and right eyes of
the viewer, the stereoscopic effect being caused by the geometry of
the spacing of the viewer's eyes and the spacing of the various
layered displays. Putilin et al. discloses that the electronic
processing to generate the calculated images necessary to deliver
each of the base stereopair images to the appropriate eye can be
accelerated by an artificial neural network. In one certain
embodiments in the patent, multiple transmissive liquid crystal
display panels are stacked one behind the other (relative to the
viewer) in conjunction with a spatial mask, such as a diffuser,
which is placed between liquid crystal displays to suppress Moire
patterns.
[0007] The layering of conventional passive or active matrix liquid
crystal display ("LCD") screens as utilized in the above patents is
not optimal for purposes of 3-D display systems. A liquid crystal
display is a thin, lightweight display device with no moving parts.
It consists of a grid of pixel elements, with each pixel element
including an electrically-controlled light-polarizing liquid
trapped in cells between two transparent polarizing sheets. The
polarizing axes of the two sheets are typically aligned
perpendicular to each other. Each pixel is supplied with electrical
contacts that allow an electric field to be applied to the liquid
inside the corresponding cell or cells.
[0008] Before an electric field is applied, long, thin molecules in
the liquid are in a relaxed state. Ridges in the top and bottom
sheet encourage polarization of the molecules parallel to the light
polarization direction of the sheets. Between the sheets, the
polarization of the molecules twists naturally between the two
perpendicular extremes. Light is polarized by one sheet, rotated
through the smooth twisting of the crystal molecules, and then
passes through the second sheet.
[0009] When an electric field is applied, the molecules in the
liquid align themselves with the field, inhibiting rotation of the
polarized light. As the light hits the polarizing sheet
perpendicular to the direction of polarization, all the light is
absorbed and the cell appears dark. In the relaxed state, however,
the whole assembly appears nearly transparent to the eye. Between
the two extremes, the cells also can be varied in increments to
produce a grayscale effect.
[0010] The liquid crystal material used in standard LCD cells
rotate all visible wavelengths equally, thus additional elements
are utilized in standard LCDs to produce a color display. On common
manner of providing a color LCD is to have each pixel is divided
into three cells, one with a red filter, one with a green filter
and the other with a blue filter. The pixel can be made to appear
an arbitrary color by varying the relative brightness of its three
colored sections. These color component cells can be arranged in
different ways, forming a kind of pixel geometry optimized for the
monitor's usage.
[0011] In all transmissive LCD panels, a slight darkening will be
evident even in the relaxed state because of brightness losses from
the backlighting source caused by the various sources, including
the polarizing sheet for the backlight, the color filters, and the
pixel grid materials. As individual transmissive LCD panels are
stacked to produce 3-D displays, such as in the manner utilized in
the Putilin et al. or Leung et al. displays, the brightness losses
multiply, producing a less vivid and sharp 3-D display providing
lower contrast and resolution. It would be desirable to preserve
brightness in such 3-D display systems.
[0012] With regard to standard two-dimensional LCD panels, several
technologies that create a single LCD panel by stacking two or
three liquid crystal cells on top of one another have been
developed in an attempt to maximize the quality of LCD images while
reducing fabrication costs. U.S. Pat. No. 5,539,547, issued to
Ishii et al, describes liquid crystal devices of the double-layer
super twist nematic ("DSTN") type that utilize plural polymer
films. The DSTN type of LCD panel utilizes two transmissive
passive-matrix LCD cells layered on top of one another to
counteract the color shifting that occurs with conventional super
twist passive matrix displays. Such DSTN displays are intended to
be a more affordable and lower power-consumption alternative to
thin film transistor ("TFT") active-matrix LCD panels, but DSTN
displays produce a lower quality picture than TFT displays. DSTN
displays have double the response time (i.e., the lag time in
forming screen graphics) of TFT displays, and typically only half
the viewing angle capability. Contrast ratio (or picture sharpness)
for DSTN displays also typically is significantly lower than for
TFT displays, thus making DSTN displays generally undesirable for
high quality graphic applications.
[0013] Phase change guest-host display ("PC-GHD") screens provide
an alternative to color filters for use in making full color LCD
displays. Instead of providing color by incorporating three
side-by-side cells and a color filter of three different colors for
each individual pixel, PC-GHD screens layer three liquid crystal
cells on top of one another for each pixel. Each of the three cells
in the pixel has a different pigment added to its liquid crystal,
and each cell can be varied in coordination with the other two
cells from fully transmissive to fully blocking to produce any
single color for the pixel. PC-GHD screens eliminate the color grid
contained in standard TFT display panels, but PC-GHD screens are
also largely undesirable for high quality graphics production as
they currently provide lower contrast than TFT displays.
[0014] In light of the prior art in the field of 3-D imaging and
transmissive display technology, it would be desirable to have a
3-D imaging system that provides high quality imaging of numerous
aspects, perspectives or views to a given single user or multiple
users in a dynamic manner. Such viewing optimally should take place
in a flexible way so that the viewer is not constrained in terms of
the location of the viewer's head when seeing the stereo image, and
should provide a maximum of contrast and brightness to the
viewer.
SUMMARY OF THE INVENTION
[0015] In light of the above drawbacks in the prior art, it is an
object of the present invention to provide for multi aspect image
viewing and the creation of dynamic and high quality 3-D image
effects viewable by one or more viewers.
[0016] It is further an object of the present invention to be able
to present an unlimited number of aspects of an image to a viewer
so as to approximate a full 3-D viewing experience without losing
any image information, brightness or quality.
[0017] It is another object of the present invention to provide the
ability to generate and display 3-D images in a dynamic manner
suitable for interactive and real-time applications by removing
sources of error and distortion from the generating and viewing of
stereoscopic images.
[0018] Additionally, it is an object of the present invention to
provide systems and related methods for 3-D imaging that improve
3-D image quality and maximize image information to the viewer.
Thus, the present invention eliminates unnecessary masks and
unnecessary obstructions from the image path of viewers when
reviewing stereo imagery, and eliminates the need for specialized
viewing gear or parallax barriers or lenticular screens within the
view path of viewers trying to visualize a 3-D scene or object.
[0019] The present invention provides a system and related methods
for three-dimensional visualization based upon stereoscopic imaging
and parallel information processing of source stereo and multi
aspect images. The source images can be processed for a single 3-D
viewing zone or multiple 3-D viewing zones for multiple users.
Preferably, the processing according to embodiments of the present
invention is adaptive in nature so as to be continually
re-processed as the location of a given viewer or viewers change.
Thus the perception of 3-D images by any given viewer is improved
by not constraining the viewer in any meaningful way.
[0020] In embodiments of the present invention, a composite
transmissive LCD panel, consisting of at least two layers of
stacked liquid crystal cells positioned on top of one another
relative to the imaging direction, is utilized to display at least
two calculated images superimposed over one another at different
distances within the panel from the viewer. Each layer of liquid
crystal cells create multiple pixels from the cells, which pixels
collectively can be operated to form an image on the liquid crystal
layer. An illumination source is positioned behind the two layers
of the composite panel to illuminate images created on the
layers.
[0021] Each liquid crystal cell layer in the composite panel of the
present invention displays a calculated image that is not one of
the source stereopair images that ultimately need to be conveyed to
the two eyes of the viewer to produce a desired 3-D effect. Rather,
the calculated images are derivatives of the source stereopair
images that interact optically in the present design to produce
collectively the stereo perspective images to be viewed. Source
image information is derived from a database of stereopairs stored
in a memory unit, or from other suitable sources of base images. A
memory unit provides a desired stereopair to a processor, which in
turn processes the calculated images to be displayed by the liquid
crystal cell layers and controls the layers accordingly. Further,
the processor controls the illumination source, such as a lamp or
other suitable lighting unit, that backlights the transmissive
composite LCD panel in order to enable viewing of the images
produced on the liquid crystal cell layers.
[0022] To calculate the derivative images for each liquid crystal
cell layer, the processor estimates the light directed to each one
of a viewer's eyes by calculating interim calculated images for
each of said transmissive cell layers, and then determines the
light directed through each discrete pixel of the front cell layer
of the transmissive composite LCD panel. The processor then
compares the estimated light for each pixel with the equivalent
light from the selected ones of the original source stereopair
images to determine an error, and then adjusts the interim
calculated images as appropriate to reduce the error in order to
keep the error for each pixel is below a set limit. Preferably, the
calculation of and refining of the derivative images is performed
by an artificial neural network.
[0023] In embodiments of the invention, the calculated image
displayed by each liquid crystal cell layer acts as a dynamic mask
for the image(s) of the other layer(s). Thus, the viewer sees no
objects or obstructions other than the 3-D image itself, in
contrast to conventional parallax barrier-type imaging systems,
where a physical barrier mask can clearly be seen. Such generating
of the 3-D image results in the absence of noise and distortion of
a visual nature such as that created by lenticular screens or
lenses.
[0024] According to embodiments of the present invention, since the
3-D image information is distributed between the two or more liquid
crystal cell layers, there is no loss of resolution as produced in
prior art systems where image information for both eyes is
displayed on a single screen or plane behind a resolution-limiting
barrier, such as a parallax barrier, lenticular screen or lens.
Further, a composite transmissive LCD panel containing integrated
multiple liquid crystal cell layers removes unnecessary elements
normally present in standard LCD panels that would otherwise
introduce losses in image brightness and cause imaging
distortions.
[0025] In certain embodiments of the invention, the calculated
images are presented to one or more viewers based upon a sensing of
one ore more viewer's positions. This viewer position signal is
generated and sent to the processor by means known in the art, such
as by an infrared ("IR") position sensor or radio frequency ("RF")
or ultrasonic position tracking sensor, where the processor then in
turn retrieves an appropriate image stereopair from the image
source for subsequent processing, presentation, and display by the
controller of the composite transmissive LCD panel. Further, in
preferred embodiments of the invention, viewer position sensors are
utilized to present a viewer with different aspects of an image as
their viewing position changes so as to allow the viewer to view
various perspectives of an image in dynamic fashion. The present
invention thereby is capable of creating a continuous 3-D image
field in a large viewing area with improved image quality, as
opposed to a discrete, stationary set of stereo viewing zones where
the image quality greatly deteriorates as the number of viewing
zones increases.
[0026] In other embodiments of the invention, a multi-user and
multi-view display capability is provided. In this manner,
different members of a viewing group each cab be provided with
different aspects of the same image, or different images
altogether, based on any number of factors such as, but not limited
to viewing location or angle. Both three-dimensional and
two-dimensional imaging for each viewer can be provided.
[0027] The embodiments of the invention having been thus described,
discussion will now be provided of preferred embodiments of the
invention as depicted in the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] The accompanying drawings, which are included to provide
further understanding of the invention and are incorporated in and
constitute part of this specification, illustrate embodiments of
the invention and together with the description serve to explain
the principles of the invention. In the drawings:
[0029] FIG. 1 is a schematic diagram illustrating a common liquid
crystal cell;
[0030] FIG. 2 is a schematic diagram illustrating the operation of
a liquid crystal cell in a relaxed state;
[0031] FIG. 3 is a schematic diagram illustrating the operation of
a liquid crystal cell in a charged state;
[0032] FIG. 4 is a schematic diagram illustrating the transmission
of light through a liquid crystal cell and polarizer sheets;
[0033] FIG. 5 is a schematic diagram illustrating the stacking of
common LCD panels in accordance with an autostereoscopic 3-D
display system;
[0034] FIG. 6 is a schematic diagram illustrating a composite
transmissive liquid crystal display panel for use within a 3-D
imaging system according to embodiments of the present
invention;
[0035] FIG. 7 is a schematic diagram illustrating 3-D light fields
created by a real object and illustrating the recreation of such
light fields utilizing a composite transmissive LCD panel according
to the present invention;
[0036] FIG. 8 is a schematic diagram depicting the orientation of a
viewer with respect to two stacked liquid crystal cell layers in
order to generate 3-D images from layered images;
[0037] FIG. 9 is an illustration of exemplary calculated images
that could be displayed on the liquid crystal cell layers of FIG. 6
to generate 3-D images;
[0038] FIG. 10 is an illustration of exemplary perceived 3-D images
that could be seen by a viewer when the images of FIG. 9 are
displayed on the composite LCD panel of FIG. 8;
[0039] FIG. 11 is a schematic diagram illustrating components of an
autostereoscopic 3-D display system utilizing a composite LCD panel
in accordance with an embodiment of the present invention;
[0040] FIG. 12 is a schematic diagram illustrating a computational
and control architecture utilized to generate 3-D images for an
autostereoscopic 3-D display system utilizing a composite LCD panel
in accordance with an embodiment of the invention;
[0041] FIG. 13 is a schematic diagram that depicts the light beam
movement from various liquid crystal cells of the composite LCD
panel to a viewer's eyes in accordance with embodiments of the
invention;
[0042] FIG. 14 is a logical flow diagram illustrating the data flow
for the operation of a display control program utilized in an
autostereoscopic 3-D display system;
[0043] FIG. 15 is a schematic diagram illustrating a neural network
diagram used to determine image data in an autostereoscopic 3-D
display system; and
[0044] FIG. 16 and FIG. 17 are illustrations of exemplary images
produced utilizing the multi-user and multi-view mode of an
autostereoscopic 3-D display system display for generating 3D
images.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0045] FIG. 1 illustrates a common liquid crystal cell 102. Many of
such cells are utilized to create pixels in the liquid crystal cell
layers of LCD panels. Each such cell 102 contains liquid crystal
material trapped within an enclosure. Liquid crystals are a class
of long, thread-like molecules that under certain conditions
exhibit isotropic fluid-like behavior, including the ability to
flow, but that also can adopt structures having higher ordering
than found in other fluids. The ordering of liquid crystal
materials is extensive on the molecular scale, but does not extend
to the macroscopic scale as might be found in classical crystalline
solids. In this manner, structural ordering in a liquid crystal
material might extend along one direction, but the material along
another direction might exhibit significant disorder. The liquid
crystal material contained within cell 102 contains many liquid
crystal molecules forming dipoles 104 trapped between two
substantially transparent opposing orientation surfaces, including
an input orientation surface 103a and an output orientation surface
103b.
[0046] Each of the orientation surfaces have an orientation feature
whereby, as result of mechanical processing of their surfaces
during fabrication, the surfaces have micro-ripples oriented in a
single direction and facing the liquid crystal material. These
micro-ripples interact with the liquid crystal dipoles 104 near the
surface in a manner that causes those dipoles near the surface to
generally orient in a direction parallel to the micro-ripples as
depicted in FIG. 1.
[0047] In common liquid crystal cells 102 as depicted in FIG. 1,
micro-ripples in the surface of the input orientation layer 103a
are oriented perpendicular with respect to the to the micro-ripples
of the output orientation layer 103b. Thus, dipoles 104 naturally
align in a spiral-like structure within the cell 102 stretching
between the orientation layers 103a and 103b. Liquid crystal
material aligned in this spiral-like structure has the optic
properties of rotating the polarization of light along with the
bending of the dipoles such that the polarization of light 100a
entering the cell 102 is naturally rotated by 90 degrees to produce
orthogonally polarized light 100b exiting the cell. In the presence
of electric field, however, dipole molecules within a given cell
can be made to align with the electrical field. In this manner, the
polarization of the input light can be controlled by passing it
through a liquid crystal cell in the presence of a controllable
electrical field.
[0048] Turning now to FIG. 2, there is depicted in cross section a
typical liquid crystal display cell 202 in a "relaxed" state
whereby the dipoles orient themselves in a spiral-like pattern in
between the input orientation layer 203a and the output orientation
layer 203b. At either end on the outside of the cell a thin
transmission conductive electrodes layer 205 covers the outside of
the orientation surfaces. Indium tin oxide ("ITO") is the material
commonly used to make the transparent conductive coatings for the
orientation surface of electronic displays cells. ITO is a mixture
of indium(III) oxide (In.sub.2O.sub.3) and tin(IV) oxide
(SnO.sub.2), typically in the proportions of about 90%
In.sub.2O.sub.3 and 10% SnO.sub.2 by weight. These electrodes
layers can be utilized to apply a controllable electric field to
the liquid crystal material.
[0049] As illustrated in FIG. 2, liquid crystal cell 202 takes
input light 200a and passes it through the substantially
transparent liquid crystal material trapped between the orientation
layers 203a and 203b where it exits the cell 202 as output light
200b having a polarization orthogonal to the input light 200a. FIG.
3 shows a liquid crystal cell 202' in a "charged" state, where an
electrical field is being applied to the electrodes layers 205. As
shown in this illustration, the dipoles 204' take an orientation in
line with the electrical field, causing the output light 200b' to
have a different polarization orientation (such as the same
orientation as the input light 200a as depicted).
[0050] In commercial LCD applications, a layer of individual liquid
crystal cells, as depicted in FIG. 1 through FIG. 3, is typically
placed between two polarizer sheets. FIG. 4 illustrates the
transmission of light through a liquid crystal cell 402 operating
in a relaxed state where the cell 402 is oriented between two
polarizer sheets 406a and 406b. As shown, input polarizer sheet
406a has an polarization orientation aligned with the orientation
of the micro-ripples of input orientation surface 403a, and output
polarizer sheet 406b likewise has an polarization orientation
aligned with the orientation of the micro-ripples of output
orientation surface 403b. Thus, polarizer sheets 406a and 406b are
oriented orthogonal to one another.
[0051] With this structure, incoherent (unpolarized) light 400a
from a back lighting source would pass through the input polarizer
sheet 406a and lose the vertical polarized component of the
incoherent light to produce polarized light 400b. With liquid
crystal cell 402 in the relaxed state with no voltage in the
electrodes (not depicted in FIG. 4), the polarized light 400b would
enter through the transparent input orientation surface 403a and
travel through the liquid crystal material. Since the dipoles (not
depicted in FIG. 4) are in the relaxed state, the liquid crystal
material naturally rotates polarization of light 400c within the
cell 402 by 90 degrees. Polarized light 400d exiting the cell 402
now has a polarization orientation orthogonal to the originally
polarized light 400b. This light is thus able to pass through the
exit polarization sheet 406b to an observer, making the cell 402 in
a relaxed state appear substantially transparent and bright to the
eye. If an electrical field was applied to the cell 402, the input
polarized light 400b could be allowed to largely pass through the
liquid crystal material without having its polarization orientation
altered, thus making output light largely unable to pass through
the output polarizer sheet 406b. Cell 402 in a charged state would
therefore appear substantially opaque and dark to the eye as very
little light would reach the viewer.
[0052] FIG. 5 is a schematic diagram illustrating the stacking of
common transmissive liquid crystal display panels 501 as would be
done in the prior art in accordance with an autostereoscopic 3-D
display system. As shown in FIG. 5, common LCD panels 501 (shown in
cross section magnified to the pixel-size level) each contain one
liquid crystal cell layer 511 trapped between sheets of electrical
conducting material 505, such as ITO. The cell layer 511 includes
various individual liquid crystal cells 502 encasing liquid crystal
material 504. The cells 502 in the layer 511 share a common input
orientation layer 503a and an output orientation layer 503b having
the orientation surface properties generally as described
above.
[0053] The transmissive LCD panel 501 further includes an input
polarizer sheet 506a and an output polarizer sheet 506b, again
arranged with their relative polarization orientations to match the
corresponding orientation surfaces 503a and 503b and being
orthogonal to one another as described above. A thin sheet of an
optically transparent material 507a, such as glass, separates the
input polarizer sheet 506a from the electrode layer 505 on top of
the input orientation layer 503a. A second thin sheet of an
optically transparent material 507b separates output polarizer
sheet 506b from components of the LCD panel that enable color
control, including a color filter assembly 509, and a black grid
508 (typically having an aperture is in the range of about 40-90%)
that provides increased contrast. In a typical color LCD panel,
each pixel is composed of three cell sections defined by the color
filter assembly 509, one with a red color filter 509a, one with a
green color filter 509b, and the other with a blue color filter
509c, as depicted. The pixel can be made to appear an arbitrary
color by individually varying the relative brightness of each its
three colored sections.
[0054] When two transmissive LCD panels 501 are used in stacked
configuration for an autostereoscopic 3-D display system as
depicted in FIG. 5 and described in detail in prior U.S. Pat. No.
6,717,728 and U.S. patent application Ser. No. 0/751,654, filed
Jan. 6, 2004, light transmission losses can become problematic.
Light from a back light device 512 is polarized by the input
polarizer sheet 506a of a first LCD panel 501 (i.e., the panel
closest to the back light device 512), passes through the optically
transparent material 507a, and then passes through liquid crystal
cells 502. Depending upon the voltage applied to the electrode
layers 505, the liquid crystal aligns in an orientation to produce
a desired polarization rotation of the input light. This, in turn,
defines the level of intensity of light exiting the output
polarizer sheet 506b. RGB coloring is provided by the color filter
assembly 509 and black grid 508 provides increased contrast.
[0055] Any polarized light that exits output polarized sheet 506b
of the first LCD panel would then pass through a diffuser or other
like device 510 that is able to rotate the polarization of the
light to match the input orientation of the next LCD panel, and
then pass through a second LCD panel (displaying a different image
than the first LCD panel) before reaching the user. Optionally, the
LCD panels could alternatively be arranged such that a device 510
is not necessary, whereby the output polarization of the back LCD
panel matches the input polarization of the front LCD panel.
Nevertheless, any brightness losses caused by the first
transmissive LCD panel are duplicated and exacerbated by the second
and any subsequent LCD panels. Table i shows typical values of
light transmission levels for particular ones of the various LCD
panel elements discussed above.
1 TABLE i Transmitted Absorbed Layer light energy, % light energy,
% Input polarizer 43 57 Liquid crystal (relaxed) 95 5 Color filter
25 75 Black grid 80 20 Output polarizer 80 20 TOTAL: 6.5 93.5
[0056] Notably, Table i indicates that approximately less than 7%
of the illuminating light from a back lighting source reaches
observer's eyes in the case of a single transmissive LCD panel. The
addition of a second LCD panel between the first LCD panel and the
viewer would decrease transmitted light to under 0.5% (even without
a diffuser placed between the LCD panels), and subsequent LCD
panels would contribute further degradation of output brightness
and quality.
[0057] To combat the problems attendant in the stacking of common
transmissive LCD panels in an autostereoscopic imaging system, the
present invention as depicted in FIG. 6 provides a composite
transmissive LCD panel 601 (shown in cross section at the pixel
level), consisting of at least two layers 611a and 611b of stacked
liquid crystal cells 602 positioned one after the other along an
imaging direction. Each layer 611a and 611b of liquid crystal cells
602 create multiple pixels, where the pixels of a given layer 611a
or 611b collectively can be operated to form an image on that
layer. The cells in each layer are controlled such that each layer
individually and simultaneously displays one of at least two
calculated images (one different calculated image for each layer)
in a manner whereby the calculated images are superimposed over one
another at different distances within the composite LCD panel 601
relative to the viewer location. An illumination source 612 is
positioned behind the composite LCD panel 602, and thus behind the
two layers 611a and 611b, to illuminate the calculated images
created on the layers. Similar to liquid crystal layers present in
prior art transmissive LCD panels, liquid crystal layers 611a and
611b include various individual liquid crystal cells 602 encasing
liquid crystal material 604 in the manner described generally
above. The cells 602 of each layer 611a or 611b share common input
orientation layers 603a or 603c and output orientation layers 603b
or 603d having the orientation surface properties and orthogonal
orientations generally as described above. Each layer 611a or 611b
is encased between sheets of electrical conducting material 605a
and 605b, and 605c and 605d, respectively, which are adapted to
apply a controllable electrical field to the enclosed cells
602.
[0058] This composite LCD panel 602 as depicted also consists of an
input polarizer sheet 606a and an output polarizer sheet 606b, one
color filter assembly 609 (containing red, green, and blue color
filter elements 609a-c), and one black grid 608. Two layers 607 of
optically transparent material, such as glass, are placed adjacent
to the polarizer sheets 606a and 606b as depicted to insulate and
protect the liquid crystal layers 611a and 611b and to space the
layers from the polarizer sheets 606a and 606b. An additional layer
607' of optically transparent material, such as glass, is situated
between the first liquid crystal layer 611a and the second liquid
crystal layer 611b binding them together. This layer 607' has a
thickness that is sufficient to insulate the liquid crystal layers
611a and 611b from one another and to create geometry suitable for
a stereo effect, as described below.
[0059] In order for the two liquid crystal layers 611a and 611b to
work in conjunction, the output orientation layer 603b for the
first liquid crystal layer 611a must be aligned along the same
polarization direction with the input orientation layer 603c of the
second liquid crystal layer 611b, as depicted. Additionally,
polarizer sheets 606a and 606b have parallel (as opposed to
orthogonal) polarizing orientations (assuming the characteristic
"twist" of each layer 611a and 611b is 90 degrees, as depicted).
Alternatively, of course, optically transparent material layer 607'
can be incorporated with a feature to change polarization of
transmitted light by 90 degrees (or an otherwise appropriate
amount) if the orientation of sheets 606a and 606b and orientation
layers 603b and 603c are not matched as depicted.
[0060] While similar LCD panel structures incorporating two or more
liquid crystal layers within a single panel have been proposed for
use as DSTN and PC-GHD liquid crystal displays, the composite
structure according to the present invention as depicted in FIG. 6
and described herein has not been employed in high resolution 3-D
imaging systems as herein described. Employing the composite
transmissive LCD panel according to the present invention in 3-D
display systems has the advantages over stacked standard LCD panels
of losing virtually no brightness and providing better image
clarity. While a standard transmissive LCD has about a 6.5%
transmission rate, the composite transmissive LCD according to the
present invention provides a comparable transmission rate of
approximately 6.2%. The effect of adding a third and subsequent
liquid crystal cell layers into the composite LCD panel is likewise
minimal.
[0061] Additionally, composite transmissive LCD panels according to
the present invention produce virtually no appreciable Moire effect
without requiring the presence of a diffusing material between the
liquid crystal layers. In the place of the diffuser, the glass or
other transparent material in between the liquid crystal layers
provides a hard structure and equal illumination across the whole
imaging area of the panel.
[0062] The principles of the composite transmissive LCD panel
according to embodiments of the present invention having been thus
described, description will now be provided with respect to an
autostereoscopic imaging system and related methods for use with
which the composite LCD panel is particularly suitable. The
autostereoscopic imaging system, as is described in detail in prior
U.S. Pat. No. 6,717,728 and U.S. patent application Ser. No.
0/751,654, filed Jan. 6, 2004, creates a three-dimensional viewing
experience by using multiple stacked electronic transmissive
displays, such as liquid crystal panels. Instead of stacking
separate LCD panels, the composite LCD panel of the present
invention can be employed as described hereafter. The 3-D imaging
system provided would therefore have increased brightness and image
quality for viewing within large and continuous viewing zones where
the 3-D images can be created dynamically on the composite LCD
panel.
[0063] FIG. 7 illustrates how humans can see real objects in three
dimensions as light 700 reflects from an object 701 and generates a
light field LF in space. The two eyes 702 of a viewer perceive this
light field differently due to each eye's different location in
space relative to the object, and the brain of the viewer processes
the different perceptions of the light field by the two eyes to
generate three-dimensional perception. FIG. 7 also shows a second
light field LF' being formed from the liquid crystal cell layers
704 within a composite LCD panel 703 controlled by a 3-D display
system whereby LF' is nearly identical to LF and creates a second
perceived 3-D image. The basic quality of any three-dimensional
imaging system depends on the magnitude of the difference between
LF and LF', i.e., how close the imaging system can come to
recreating LF. If the second light field LF' is recreated to be
nearly the same as the original light field LF, the viewer of LF'
will perceive the same object image in three dimensions.
[0064] A preferred 3-D imaging system utilizes two or more stacked
transmissive liquid crystal cell layers 704 within a composite LCD
panel 703 as shown in FIG. 7, but with each layer cooperating to
display derivative images of the stereopair images that are desired
to be displayed to the viewer's two eyes. The derivative images
interact and effectively mask one another to produce collectively
the stereo image to be viewed. As shown in FIG. 8, the composite
LCD panel in embodiments of the present invention provides liquid
crystal cell layers stacked in an orientation relative to the
viewer (viewer position denoted in FIG. 8 by the left and right eye
802a and 802b, respectively). As depicted in the drawing, each eye
802a and 802b has a different view path to the back B and front F
cell layers (as shown by view lines 805-808), which view path
causes the images on the panels to be summed together and perceived
by the viewer as different stereoscopic images for the eyes 802a
and 802b.
[0065] FIG. 9 illustrates an example of such derivative images 901
and 902 adapted for the back cell layer B and front cell layer F,
respectively. As depicted in the drawing, the derivative images
displayed on each of the layers can appear blurred and chaotic when
viewed independently and separately. However, when viewed
simultaneously with the cell layers B and F in the proper
orientation within the composite LCD panel 801 as depicted in FIG.
8, the derivative images will produce appropriate stereoscopic
images 1001 and 1002 that reach the left and right eyes of the
viewer, respectively, as depicted in FIG. 10.
[0066] To calculate the derivative images for each cell layer in
embodiments of the invention, the processor estimates the light
directed to each one of a viewer's eyes by calculating interim
calculated images for each cell layer, and then determines the
light directed through each discrete pixel of the front cell layer
as a result of the images created simultaneously on both layers.
The processor then compares the estimated light for each pixel with
the equivalent light from the selected ones of the original source
stereopair images to determine an error, and then adjusts the
interim calculated images as appropriate to reduce the error in
order to keep the error for each pixel below a set limit.
[0067] In accordance with an embodiment of the invention, an
iterative algorithm evaluates the differences between the generated
images and the original image. Based on the differences between
them, the algorithm dictates screen imaging adjustments. These
screen adjustments cause changes to the generated images making
them more identical replicas of the original (i.e. approaching
maximum exactness). For example, this iterative process can require
several iterations, such as 3 to 7 iterations, to render each frame
within acceptable error.
[0068] FIG. 11 shows the basic components of a display system 11 in
accordance with a preferred embodiment of the invention. In the
drawing, a distant and nearest (hereinafter also called "near")
liquid crystal cell layers 4 and 6 are separated by a known gap
within a composite LCD panel 5. The liquid crystal cell layers
within the composite LCD panel are controlled by a computing device
1, such as a personal computer, a video controller, or other
suitable digital processing device. As will be discussed in detail
below, the display system depicted relies on the calculation of
images by the computing device 1 that are then displayed on the
distant and near liquid crystal cell layers 4 and 6 to produced
perceived stereo images in the viewer eyes. The computing device 1
also controls a lighting source 2 adapted to backlight the
composite LCD panel 5.
[0069] FIG. 12 illustrates the detail for the computing device 1,
depicting the computational and control architecture utilized to
generate 3-D images in accordance with that embodiment of the
invention. Although disclosed in this embodiment as including a
viewer position signal input 10, it will be understood by one of
skill in the art that the invention can also be practiced without
this feature by defining a set viewing zone or multiple set viewing
zones. The invention utilizes a database of stereopairs or aspects
which are also provided as an input 8 to the memory unit 12. Memory
unit 12 has several functions. Initially memory unit 12 will
extract and store a particular stereopair from the input 8 source
(such as a database in memory or storage). This stereopair will
correspond to an initial viewing position. As noted above, a viewer
position sensor 10 can provide a viewer position signal to
processor 14.
[0070] Generally, a minimum of two image information streams,
corresponding to left eye and right eye images, are needed to
generate a 3-D image in embodiments of the present invention. While
above it was stated that the stereopair source images could be
stored in and retrieved from a database in another memory or
storage location (including stored previously in memory 12), the
source image information may come ultimately from a variety of
sources. For example, the information streams may include one or
more pairs of camcorders or paired video streams for live 3-D video
or recorded 3-D video, left and right images of one object (e.g.,
for photos) and left and right views from a digital 3-D scene
(e.g., for games).
[0071] All during the viewing session, the viewer position signal
10 is constantly monitored and provided to processor 14. Depending
upon the viewer position and subsequent error processing as noted
(below), information from processor 14 regarding viewer position 10
(or preset location of the user for stationary viewing zones) is
provided to memory 12 for subsequent extraction of the stereopair
aspects from the database and recalculation of derived images for
the displays 4 and 6. Thus the present invention can constantly
provide an updated series of stereopairs to the processor based
upon the input viewer position signal if the viewer desires to see
the 3-D object from various positions. If the viewer desires to see
a single 3-D view of an object, regardless of the viewing position,
the viewer position signal input 10 can be used to determine the
optical geometry used in the required processing. As will be
readily appreciated by one skilled in the art, multiple viewer
position signals can similarly be used to created multiple viewing
zones (including with different images or image aspects) as is
described below.
[0072] Memory 12 provides the desired stereopair to the processor
14 to produce calculated images. The calculated images can be
directly sent from processor 14 to LCD panel and lighting unit
control 16 or stored in memory 12 to be accessed by control unit
16. Unit 16 then provides the calculated images to the appropriate
liquid crystal cell layers 4 and 6 within the composite LCD panel 5
as well as controls the lighting from source 2 that illuminates the
layers 4 and 6. Processor 14 can also provide instructions to LCD
and lighting control unit 16 to provide the appropriate
illumination.
[0073] It should be noted that memory 12 holds the accumulated
signals of individual cells or elements of each liquid crystal cell
layer. Thus the memory unit 12 and processor 14 have the ability to
accumulate and analyze the light that is traveling through relevant
screen elements of the composite LCD panel toward the right and
left eyes of the viewer which are identified by the processor 14
based upon the set viewing zone(s) or the viewer position signal
10.
[0074] FIG. 13 schematically depicts the light beam movement from
display panels to a viewer's eyes. As illustrated in FIG. 13, two
light beams will come from back lighting source 22 through the
arbitrary cell z 28 on the near liquid crystal cell layer 18 in
order to come through the pupils of eyes 34 and 36. These beams
will also first cross distant liquid crystal cell layer 20 at the
points a(z) 26 and b(z) 24. The image in the left eye 36 is a
computation of:
SL.sub.z=N.sub.z*D.sub.a(z),
[0075] where N is the intensity of the pixel on the near layer 18
and D is the intensity of the pixel on the distant layer 20.
[0076] For right eye 34, respectively, the computation is:
SR.sub.z=N.sub.z*D.sub.b(z).
[0077] When light is directed through all the pixels z(n) of near
cell layer 18, the images SL and SR are formed on the retinas of
the viewer. The aim of the calculation is a optimizing of the
calculated images on the near and distant layers 18 and 20 to
obtain
SL.fwdarw.L, and
SR.fwdarw.R.
[0078] One can prove that it is impossible to obtain an exact
solution for the arbitrary L and R images. That is why the present
invention seeks to find an approximated solution in the possible
distributions for N and D to produce a minimum quadratic disparity
function (between target and calculated images): 1 ( SL - L ) N , D
min ( SR - R ) N , D min
[0079] where .rho.(x) is a function of the disparity, such as, for
example, a quadratic function of the form
.rho.(x)=x.sup.2,
[0080] with the limitation of pixel intensity to
0.ltoreq.N.ltoreq.255, 0.ltoreq.D.ltoreq.255.
[0081] An artificial Neural Network ("NN"), such as described below
with respect to FIG. 9, may be used for this problem solving
because it permits parallel processing and DSP integration.
[0082] Referring now to FIG. 14, the data flow for the manipulation
of the images of the present invention is illustrated. As noted
earlier the memory unit 12, processor 14, and LCD control and
luminous control 16 regulate the luminous radiation emanating from
source 22 and the transmissivity of the distant layer 20 and the
near layer 18.
[0083] Information concerning multiple discreet two dimensional
(2-D) images (i.e., multiple calculated images) of an object, each
of which is depicted in multiple different areas on the LCD
screens, and, optionally, information about positions of the right
and left eyes of the viewer are adjusted by the processor 14.
[0084] Signals corresponding to the transmission of a portion of
near layer 18 (signal 1428) and the transmissivity of the distant
layer 20 corresponding to the luminous radiation of those portions
of the image of the left and right eye respectively (signals 1424
and 1432) are input to the processor following the set program. The
light signals from the cells of all layers that are directed toward
the right and left eye of each viewer are then identified. In this
example signals from cells 28 and 26 are all directed toward the
left eye of the viewer 36 and signals from block 28 and 24 are
directed the right eye of the viewer 34.
[0085] Each of these left and right eye signals is summed 1438 to
create a value for the right eye 1442 and for the left eye 1440.
These values are then compared in a compare operation 1448 to the
relevant parts of the image of each aspect and to the relevant
areas of the image of the original source object aspects 1444 and
1446. An adjustment 1450 would then be made to the original values
in an attempt to reduce the error.
[0086] Keeping in mind that the signal is a function of the
location of the viewer's eyes, the detected signal can vary to some
extent. Any errors from the comparison are identified for each cell
of the near and distant liquid crystal cell layers. Each error is
then compared to the set threshold signal and, if the error signal
exceeds the set threshold signal, the processor control changes the
signals corresponding to the luminous radiation of at least part of
the distant layer 20 cells as well as changes the transmissivity of
at least part of the near layer 18 cells.
[0087] If the information concerning the calculated images of the
object changes, as a result of movement of the viewer position, the
processor senses that movement and inputs into the memory unit
signals corresponding to luminous radiation of the distant layer
cells as well as the transmissivity of the near layer cells until
the information is modified. When the viewer position varies far
enough to require a new view, that view or image is extracted from
the database and processed.
[0088] FIG. 15 shows a neural network architecture that is applied
to the problem described above in accordance with an embodiment of
the invention. In calculating the images on the far and near
screens, it helps to assume that there are L and R, a left and a
right pair of stereo source images, and a constant viewing-zone
(assuming the viewer's eye position is constant). A neural network
of the invention replicates the function of the human eye by
generating an image through two liquid crystal cell layers. To
generate these images, the neural algorithm reduces the differences
between the original light field of the object (the source images)
and the light field generated by the stacked liquid crystal cell
layers. The difference between the light fields is called the
maximum exactness (or minimum error), and is reduced until
sufficient exactness within the range of human perception is
achieved. The neural network architecture shown in FIG. 15 is a
three layer neural network. An input layer 52 consists of one
neuron that spreads the unit excitement to the neurons of the
hidden layer 54. The neurons of the hidden layer 54 form two groups
that correspond to the near and distant layers. The neurons of an
output layer 56 forms two groups that correspond to images SL and
SR. The number of neurons corresponds to the number of liquid
crystal layer pixels. Synaptic weights Wij that corresponds to the
near and distant layers is an adjusting parameter. Synaptic
interconnection between hidden layer neurons corresponds to the
optical scheme of the system: 2 V j , k = { 1 - if j = k & k ,
a ( k ) , b ( k ) is on the same line or j = k & k , c ( z ) ,
d ( z ) is on the same line 0 - otherwise
[0089] Nonlinear functions are a sigmoid function in the value
[0-255]: 3 F ( x ) = 255 1 + - x ,
[0090] or a saturation function of the form 4 F ( x ) = { 0 - if x
< 0 x - if 0 x 255 255 - if x > 255 .
[0091] The functioning of the NN can be described by: 5 X j = F ( j
W ij Inp i ) = F ( W ij ) = { D j - if j D N j - if j N - outputs
of hidden layer . Y k = F ( k V ik X j ) - outputs of the NN .
[0092] The output signal in any neuron is a summation of at least
one signal from the distant and near layers. The output of the NN
corresponding to the left and right eye of the viewer, is
Y.sub.k(left)=F(X.sub.z*X.sub.a(z))=F(N.sub.z*D.sub.a(z))
Y.sub.k(right)=F(X.sub.z*X.sub.b(z))=F(N.sub.z*D.sub.b(z))
[0093] The error function is: 6 E = k ( Y k ( left ) - L k ) + k (
Y k ( right ) - R k )
[0094] that is the summation of all the errors. From above, it is
evident that when E.fwdarw.0 while NN learning, the output of the
hidden layer will correspond to the desired calculated images to be
illuminated on the screens.
[0095] In the initial step of NN learning, the weights Wij have
random values. For acceleration of the learning process, weights
can be initialized in accordance with the initial selected
stereopair. A back propagation method (BackProp) was used to teach
the NN: 7 W ij ( new ) = W ij ( old ) - E W ij
[0096] where .alpha. accounts for the velocity of the learning. An
acceptable accuracy can typically be obtained at 10-15 iterations,
and for some images the extremely low errors can be achieved in 100
iterations. The calculations show the strong dependence between the
level of errors and the parameters of the optical scheme, such as
the shape of the L and R images, the distance between the near and
distant cell layers, and the viewer eye position.
[0097] For obtaining more stable solutions for small variations of
the optical parameters, two alternative methods can be used. The
first method involves modification of the error function, by adding
a regularization term: 8 E = k ( Y k ( left ) - L k ) + k ( Y k (
right ) - R k ) + W ij 2 2
[0098] where .beta.--is a regularization parameter.
[0099] The second method involves randomly changing the position of
the viewer eye by a small amount during the training of the NN.
Both of these methods can be used for enlarging of the area of
stereo viewing.
[0100] Training methods other than "BackProp" can also be used, for
example, a conjugated gradients method: 9 W ij ( t ) = W ij ( t - 1
) + ( t ) S ij ( t - 1 ) , S ij ( t ) = - G ij ( t ) + ; G ij ( t )
r; 2 ; G ij ( t - 1 ) r; 2 S ij ( t - 1 ) G ij ( t ) = E W ij
[0101] which is a variant of Fletcher-Reeves. This will accelerate
the training procedure 5-10 times.
[0102] A typical liquid crystal cell layer suitable for use in the
present invention corresponds to a 15" (or larger) active-matrix
liquid crystal display layer providing a resolution of
1024.times.768 or greater. In a composite LCD panel utilizing such
a 15" cell layers, preferably the distance between the layers is
less than approximately 5 mm. A suitable computer system includes
an Intel Pentium III-500 MHz equivalent or faster processor, for
stereo image processing, and the mask comprises a diffuser. The
computer should be sufficient to emulate the neural network for
obtaining the calculated images that must be illuminated on the
near and distant screens in order to obtain separated left-right
images in predefined areas. The neural network emulates the optical
interaction of the displayed derived images as described above and
takes into account the viewer's eye position in order to minimize
the errors in the stereo image and dynamically produce a perceived
3-D image.
[0103] Given the compact nature of the arrangement of multiple
liquid crystal cell layers in certain embodiments of the invention,
it is important to provide suitable cooling for the composite LCD
panel to prevent overheating. One way suitable cooling can be
provided is by utilizing an arrangement of fans within the display
casing (which typically, in commercial embodiments, would encase at
least the composite LCD panel and light source) to provide a
cooling cross-flow of air.
[0104] As described above, the inclusion of a means for inputting a
viewer position signal enables display systems according to the
present invention to use both a set image viewing zone (or zones)
or no zones that allow viewers to move without losing 3-D effect.
The algorithms used to determine components of the derived images
(such as SL and SR above) use variables for the optical geometry,
and the viewer position signal is used to determine those
variables. Also, the viewer position signal may be used to
determine which stereopair to display, based on the optical
geometry calculation, when the display is in a mode that allows
viewer position changes to change the image view or perspective
seen by the viewer. Numerous known technologies can be used for
generating the viewer position signal, including known head/eye
tracking systems employed for virtual reality (VR) applications,
such as, but not limited to, viewer mounted RF sensors,
triangulated IR and ultrasound systems, and camera-based machine
vision using video analysis of image data.
[0105] The signals corresponding to the transmissivity of the near
and distant layers' cells are input into the memory unit by means
of the processor following the set program. The next step is to
identify the light signals that can be directed from the cells of
all the stacked liquid crystal cell layers towards the right and
left eyes of at least one viewer. Then compare the identified light
signals directed towards each eye to the corresponding areas of the
set 2-D stereopair images of the relevant object.
[0106] For each cell of each layer, the error signal is identified
between the identified light signal that can be directed towards
the relevant eye and the identified relevant area of the stereo
picture of the relevant object aspect that the same eye should see.
Each received error signal is compared to the set threshold signal.
If the error signal exceeds the set threshold signal, the mentioned
program of the processor control modifies the signals corresponding
to the layer cells. The above process is repeated until the error
signal becomes lower than the set threshold signal or the set time
period is up.
[0107] It is also possible to solve the calculations for the case
of two (or more) different objects reconstructed in two (or more)
different directions for two (or more) viewers. It must be
mentioned specifically that all calculations can be performed in
parallel utilizing, for example, DSP processors designed for this
purpose. Thus, the present invention can be used for multi-viewing
display emulation. It should also be noted that the system of the
present invention may also be used with multiple viewers observing
imagery simultaneously. The system simply recognizes the individual
viewers' positions (or sets specific viewing zones) and displays
images appropriate for the multiple viewers.
[0108] The algorithm in accordance with the invention can be
adapted for use with different hardware configurations including a
computer central processing unit (e.g. Intel chips) and 3-D video
cards (e.g., nVidia GeForce, or ATI Radeon) supporting dual monitor
configurations. Furthermore, hardware such as known 3-D
accelerators can be used operate the algorithm more quickly.
[0109] As will be readily appreciated by one skilled in the area,
3-D displays created according to the principles of the present
invention can be adapted to operate in several different modes.
Such displays can work in stereo and multi-zone modes (M screens to
provide views to N zones), in a more traditional electronic
parallax barrier or lenticular stereo display mode, a dynamic noise
stereo display mode (i.e., providing dynamic noise in a front
screen and calculated images in second screen), a RF secure display
mode (i.e., placing a specialized image in the front panel to make
the back image visible for user, but invisible for radio--frequency
screening) and a multi-user/multi-view (or "Family") display mode.
Further, the 3-D images produced by the present invention can be
further enhanced by application of known regularization
processes.
[0110] FIG. 16 and FIG. 17 provide illustrations of the images
encountered in a "Family" mode display. In this example, different
members of a viewing group (e.g. where the group is a "family")
each see different aspects of the same image, or different images
altogether, based on any number of factors such as, but not limited
to viewing location or angle. As depicted in FIG. 16, the derived
images 1601 and 1602 actually displayed on the liquid crystal cell
layers of the composite LCD panel create a completely different
perceived image 1703 for the first viewer (see FIG. 17), located at
a first viewing position, and a second perceived image 1704 for a
second viewer, located at a viewing position different from the
first viewing position. The images for each viewer can both be
stereoscopic (3-D), both be two-dimensional, or be a mixture of the
two. As the number of viewers and different independent views
increases, improved image quality can be obtained by increasing the
number of liquid crystal cell layers within a composite LCD panels,
or alternatively the number of composite LCD panels themselves, to
increase the overall amount of image data that can be relayed to
the viewers.
[0111] As will be readily appreciated by one skilled in the art, in
certain embodiments of the invention, the light source can be a
substantially broadband white-light source, such as an incandescent
lamp, an induction lamp, a fluorescent lamp, or an arc lamp, among
others. In other embodiments, light source could be a set of
single-color sources with different colors, such as red, green, and
blue. These sources may be light emitting diodes ("LEDs"), laser
diodes, or other monochromatic and/or coherent sources.
[0112] In embodiments of the invention, the liquid crystal display
panels comprise switchable elements. As is known in the art, by
adjusting the electric field applied to each of the individual
color panel pairs, the system then provides a means for color
balancing the light obtained from light source. In another
embodiment, each color panel system can be used for sequential
color switching. In this embodiment, the panel pairs include red,
blue, and green switchable panel pairs. Each set of these panel
pairs is activated one at a time in sequence, and display cycles
through blue, green, and red components of an image to be
displayed. The panel pairs and corresponding light sources are
switched synchronously with the image on display at a rate that is
fast compared with the integration time of the human eye (less than
100 microseconds). Understandably, it is then possible to use a
single pair of monochromatic displays (i.e., LCDs lacking a color
filter) to provide a color three-dimensional image.
[0113] Utilizing a composite LCD panel in this technique improves
the image quality in comparison with parallax barrier systems due
to the total use of the cells of all the layers for the information
transmission. The preferred embodiments disclosed can also identify
the number of the viewers as well as the positions of the right and
left eyes of each viewer and perform the above-mentioned procedures
to realize the techniques in accordance with the identified eye
positions of all the viewers. Such a system makes it possible for
several viewers to receive visual information with the perception
of the stereoscopic effect simultaneously.
[0114] The system and related methods having been shown and
described herein, it will be apparent to those skilled in the art
that other embodiments of the present invention are possible
without departing from the scope of the invention as disclosed and
claimed.
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